Way-Finding During The Fur Trade Trading furs for European manufactured goods required carrying large loads from England through North America over thousands of kilometres of ocean, river, and trail. While parts of this network of rivers and trails were well-known, the knowledge was often fragmented and local, developed for shorter-range trading or communication. Without global knowledge of location and way-finding, one could wind up at the Artic Ocean while on the way to the Pacific, as Mackenzie did in 1789. Determined to find a way to the Pacific, Mackenzie went back to England to study astronomical navigation - finding one's way by stars and planets. Position on the Eath's globe is determined by two distances-the latitude (distance north or south of the equator), and the longitude (distance east or west of Greenwich, England). Latitude can be measered by measuring the angles of the sun several times during the day and referring to printed tables of position and latitude. Mackenzie carried along a chronometer and sextant for sighting the sun and measuring these angles. Longitude is more difficult to determine. Accurate techniques were not developed until the middle 1700s, shortly before Mackenzie began his voyages. To find longitude, you need to compare your local time -determined by the angles of the sun- with the time at some known longitude -usually the "zero degree" longitude of Greenwich, England. Mackenzie used the eclipses of two of Jupiter's moons to determine Greenwich time while on the Pacific Ocean. The observations had to be made on a clear night, with a reasonably powerful...con't

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